Tungsten-doped indium oxide structures and methods

ABSTRACT

Methods of forming transparent conducting oxides and devices formed by these methods are shown. Monolayers that contain tungsten and monolayers that contain indium are deposited onto a substrate and subsequently processed to form tungsten-doped indium oxide. The resulting transparent conducing oxide includes properties such as an amorphous or nanocrystalline microstructure. Devices that include transparent conducing oxides formed with these methods have better step coverage over substrate topography and more robust film mechanical properties.

TECHNICAL FIELD

This application relates generally to transparent conducting oxidematerials, fabrication methods, and electronic devices in which suchconducting oxides are used.

BACKGROUND

Transparent conducting oxides (TCOs) are extensively used in electronicapplications where electrical conduction and optical transparency areboth required. Some example applications include liquid crystal displays(LCDs) organic light emitting diodes (LEDs), solar cells, etc. Indiumtin oxide (ITO) is widely used because of it's high transparency, lowresistivity, and high work function. One drawback to ITO is limitedchemical stability at higher temperatures. It is also desirable tofurther reduce electrical resistivity in TCOs.

Tungsten-doped indium oxide (IWO) materials are being explored aspossible alternatives to TCOs such as ITO due to properties such as hightransparency and high carrier mobility. However, IWO formation methodssuch as metal sputtering and subsequent oxidation do not provide filmsor other structures of the quality and cost necessary for some deviceapplications.

What are needed are methods to form IWO films that produce improved IWOstructures with improved properties such as transparency, resistivity,crystallinity, step coverage, mechanical properties, etc. What are alsoneeded are improved IWO films, structures, etc. and devices utilizingthese IWO oxides that take advantage of the improved properties.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a surface of an electronic device in a stage of processingaccording to an embodiment of the invention.

FIG. 1B shows a surface of an electronic device in another stage ofprocessing according to an embodiment of the invention.

FIG. 2 shows a method of forming a material layer or structure accordingto an embodiment of the invention.

FIG. 3 shows a material deposition system according to an embodiment ofthe invention.

FIG. 4 shows a block diagram of an electronic device according to anembodiment of the invention.

FIG. 5 shows a block diagram of an image sensor according to anembodiment of the invention.

DETAILED DESCRIPTION

In the following detailed description of the invention, reference ismade to the accompanying drawings that form a part hereof and in whichis shown, by way of illustration, specific embodiments in which theinvention may be practiced. These embodiments are described insufficient detail to enable those skilled in the art to practice theinvention. Other embodiments may be utilized and structural, logical,and electrical changes may be made without departing from the scope ofthe present invention.

The terms “wafer” and “substrate” used in the following descriptioninclude any structure having an exposed surface with which to form anelectronic device or device component such as a component of anintegrated circuit (IC). The term substrate is understood to includesemiconductor wafers. The term substrate is also used to refer tosemiconductor structures during processing and may include other layers,such as silicon-on-insulator (SOI), etc. that have been fabricatedthereupon. Both wafer and substrate include doped and undopedsemiconductors, epitaxial semiconductor layers supported by a basesemiconductor or insulator, as well as other semiconductor structureswell known to one skilled in the art. The term conductor is understoodto include semiconductors and the term insulator or dielectric isdefined to include any material that is less electrically conductivethan the materials referred to as conductors. The term transparent isdefined as a property of a material that transmits a substantial portionof incident electromagnetic energy in a give frequency range. Examplesof electromagnetic energy ranges include visible frequency light,infrared, ultraviolet, etc. or combinations of frequency ranges. Theterm monolayer is defined as a material layer that is substantially onemolecule thick. In some embodiments, one molecule includes one atom,while other molecules are comprised of several atoms. The term monolayeris further defined to be substantially uniform in thickness, althoughslight variations of between approximately 0 to 2 monolayers results inan average of a single monolayer as used in description below.

The term “horizontal” as used in this application is defined as a planeparallel to the conventional plane or surface of a wafer or substrate,regardless of the orientation of the wafer or substrate. The term“vertical” refers to a direction perpendicular to the horizontal asdefined above. Prepositions, such as “on,” “side” (as in “sidewall”),“higher,” “lower,” “over,” and “under” are defined with respect to theconventional plane or surface being on the top surface of the wafer orsubstrate, regardless of the orientation of the wafer or substrate.

FIG. 1A shows a substrate surface 100 of an electrical device such as asemiconductor based device. The surface 100 includes variations insurface topography as illustrated by feature 110 such as a trench.Although a trench 110 is illustrated as an example, other variations intopography, both above and below an average surface level are useful todescribe embodiments of the invention.

An electronic device 120 is also shown in a rough block diagram form inFIG. 1A. Examples of electronic devices 120 include optical electronicdevices such as active pixel sensors, photovoltaic devices, lightemitting diode (LED) devices, plasma display screen devices etc. Otherdevices that benefit from adjacent structures with optical transparencyare within the scope of the invention.

FIG. 1B shows a deposited transparent conducting oxide layer 130including tungsten and indium formed over the surface 100. In oneembodiment, the transparent conducting oxide layer 130 includes atungsten-doped indium oxide (IWO) layer. As discussed above,tungsten-doped indium oxide provides a number of useful properties overother transparent conducting oxides such as indium tin oxide. Advantagesinclude high transparency and low electrical resistivity. The layer 130is shown forming a conformal layer over challenging topography such asfeature 110. The layer 130 is also shown covering at least a portion ofthe electronic device 120.

FIG. 1B illustrates an incoming beam 140 of electromagnetic energy suchas visible frequency light, UV light, etc. Selected devices within thescope of the invention include devices such as photovoltaic, activepixel sensors, etc. that benefit from the ability to receive theincoming beam through a transparent layer 130. FIG. 1B also illustratesan outgoing beam 142. Selected devices within the scope of the inventioninclude likewise include devices such as light emitting diodes, plasmadisplay screen emitters, etc. that benefit from the ability to transmitan outgoing beam through a transparent layer 130. One use of transparentconducting oxides in conjunction with devices such as these includesinterconnection circuitry between devices, to an edge of an array or achip, to a power supply, etc.

The transparent conducting oxide layer 130 is formed using monolayerdeposition methods as described in embodiments below. Methods includeatomic layer deposition (ALD) techniques, chemically self-limitingtechniques, or other techniques that form monolayers with controlledthickness. As defined above, the term monolayer defines a layer that issubstantially one molecule or one atom thick. Although substantially onelayer thick, some variation on the order of 0 to 2 molecules is withinthe scope of the invention.

The methods described form a unique structure compared to otherdeposition methods. Using monolayer deposition methods described below,a transparent conducting oxide structure can be formed with stepcoverage over surface topography that is superior to other depositiontechniques such as conventional CVD, sputtering, and laser ablation.Selected monolayer processing methods can provide a substantiallyamorphous transparent conducting oxide structure that is not possibleusing other deposition techniques. Other processing variations provide afine crystal distribution such as a nanocrystalline transparentconducting oxide structure. Micro-scale and nano-scale crystalstructures provide unique physical properties such as highly durablefilms.

FIG. 2 shows a flow diagram of an example method of forming atransparent conducting oxide according to an embodiment of theinvention. In operation 210, a monolayer that includes tungten isdeposited. In one embodiment, the first monolayer is tungsten oxide. Aprimary example of tungsten oxide includes WO₃. In one embodiment, thefirst monolayer is tungsten nitride. One example of tungsten nitrideincludes W₂N. In one embodiment the monolayer is tungsten metal.

In operation 220, a monolayer that includes indium is deposited. In oneembodiment, the second monolayer is indium oxide. A primary example ofindium oxide includes In₂O₃. In one embodiment the monolayer is indiummetal.

Several layers including tungsten containing layers and indiumcontaining layers can be built up to form a laminate structure. Morelayers can be used to form thicker structures. Further, as discussed inmore detail below, the relative number of each layer can be adjusted toprovide any desired ratio between tungsten and indium. By usingmonolayer deposition, the thickness and/or the ratio between layermaterials is precisely controlled. Although two layers includingtungsten and indium are described, the invention is not so limited.Other layers are also included in selected embodiment to provideadditional chemical and structural options.

In operation 230, the layers in the laminate are processed to form atransparent conducting oxide structure. Processing of laminateembodiments such as W₂N/In₂O₃ includes annealing or activating diffusionprocesses to mix the layers and provide a tungsten-doped indium oxide.Processing of metal layer embodiments such as W/In includes oxidizingthe layers and mixing the layer to provide a tungsten-doped indiumoxide. Final chemistry of the dopant and matrix will depend on theapplication of the transparent conducting oxide and any relatedelectronic device.

Processing variable such as temperature and pressure, duration, etc. arechosen to tailor a desired structure morphology. For example, in oneembodiment the individual layers in the laminate are deposited in asubstantially amorphous state. By processing at a low temperature, theamorphous characteristics of the original layer is substantiallypreserved, and the resulting transparent conducting oxide issubstantially amorphous. Likewise, other processing variables can alsobe chosen to produce a micro-crystalline or nano-crystalline transparentconducting oxide microstructure. As mentioned above, microstructuressuch as nano-crystallinity provide advantages such as improved filmdurability.

As discussed above, monolayer deposition of material layers provides anumber of advantages for transparent conducting oxide structures. Onemethod of depositing monolayers includes atomic layer deposition (ALD).ALD was developed in the early 1970's as a modification of chemicalvapor deposition (CVD) and is also called “alternatively pulsed-CVD.” InALD, gaseous precursors are introduced one at a time to the substratesurface mounted within a reaction chamber (or reactor). Thisintroduction of the gaseous precursors takes the form of pulses of eachgaseous precursor. Between the pulses, the reaction chamber is purgedwith a gas, which in many cases is an inert gas, or evacuated.

In a chemisorption-saturated ALD (CS-ALD) process, during the firstpulsing phase, reaction with the substrate occurs with the precursorsaturatively chemisorbed at the substrate surface. Subsequent pulsingwith a purging gas removes precursor excess from the reaction chamber.

The second pulsing phase introduces another precursor on the substratewhere the growth reaction of the desired film takes place. Subsequent tothe film growth reaction, reaction byproducts and precursor excess arepurged from the reaction chamber. With favorable precursor chemistrywhere the precursors adsorb and react with each other on the substrateaggressively, one ALD cycle can be preformed in less than one second inproperly designed flow type reaction chambers. Typically, precursorpulse times range from about 0.5 sec to about 2 to 3 seconds.

In ALD, the saturation of all the reaction and purging phases makes thegrowth self-limiting. This self-limiting growth results in large areauniformity and conformality, which has important applications forapplications such as planar substrates, deep trenches, and in materialdeposition on porous materials, other high surface area materials,powders, etc. Examples include, but are not limited to porous silicon,alumina powders, etc. Significantly, ALD provides for controllingdeposition thickness in a straightforward, simple manner by controllingthe number of growth cycles.

The precursors used in an ALD process may be gaseous, liquid or solid.Typically, liquid or solid precursors are volatile. The vapor pressuremust be high enough for effective mass transportation. Also, solid andsome liquid precursors are heated inside the reaction chamber andintroduced through heated tubes to the substrates. The necessary vaporpressure is reached at a temperature below the substrate temperature toavoid the condensation of the precursors on the substrate. Due to theself-limiting growth mechanisms of ALD, relatively low vapor pressuresolid precursors can be used though evaporation rates may somewhat varyduring the process because of changes in their surface area.

There are several other considerations for precursors used in ALD.Thermal stability of precursors at the substrate temperature is a factorbecause precursor decomposition affects the surface control. ALD isheavily dependent on the reaction of the precursor at the substratesurface. A slight decomposition, if slow compared to the ALD growth, canbe tolerated.

The precursors chemisorb on or react with the surface, though theinteraction between the precursor and the surface as well as themechanism for the adsorption is different for different precursors. Themolecules at the substrate surface react aggressively with the secondprecursor to form the desired solid film. Additionally, precursorsshould not react with the film to cause etching, and precursors shouldnot dissolve in the film. Using highly reactive precursors in ALDcontrasts with the selection of precursors for conventional CVD.

The by-products in the reaction are typically gaseous in order to allowtheir easy removal from the reaction chamber. Further, the by-productsshould not react or adsorb on the surface.

In a reaction sequence ALD (RS-ALD) process, the self-limiting processsequence involves sequential surface chemical reactions. RS-ALD relieson chemistry between a reactive surface and a reactive molecularprecursor. In an RS-ALD process, molecular precursors are pulsed intothe ALD reaction chamber separately. The metal precursor reaction at thesubstrate is typically followed by an inert gas pulse or chamberevacuation to remove excess precursor and by-products from the reactionchamber prior to pulsing the next precursor of the fabrication sequence.

Using RS-ALD, films can be layered in equal metered sequences that areessentially identical in chemical kinetics, deposition per cycle,composition, and thickness. RS-ALD sequences generally deposit less thana full layer per cycle. Typically, a deposition or growth rate of about0.25 to about 2.00 Å per RS-ALD cycle can be realized.

RS-ALD provides for high continuity at an interface compared with othertechniques such as CVD; conformality over difficult topography on asubstrate; use of low temperature and mildly oxidizing processes; growththickness dependent solely on the number of cycles performed, andability to engineer multilayer laminate films with resolution of one totwo monolayers. RS-ALD allows for deposition control on the order onmonolayers and the ability to deposit monolayers of amorphous films.

RS-ALD processes provide for robust deposition of films or otherstructures. Due to the unique self-limiting surface reaction materialsthat are deposited using RS-ALD, such films are free from processingchallenges such as first wafer effects and chamber dependence.Accordingly, RS-ALD processes are easy to transfer from development toproduction and from 200 to 300 mm wafer sizes in production lines.Thickness depends solely on the number of cycles. Thickness cantherefore be dialed in by controlling the number of cycles.

Laminate structures of multiple layers formed using ALD can also besubsequently processed to mix the individual layers together. Forexample, a laminate structure can be annealed to mix a plurality ofdifferent layers together, thus forming an alloy or a mixture of layerchemistries. By forming a laminate structure using ALD, and subsequentlymixing the layers, the chemistry of the resulting structure is preciselycontrolled. Because the laminate is made up of self-limiting monolayersover a known surface area, the number of molecules from each individuallayer are known to a high degree of accuracy. Chemistry can becontrolled by adding or subtracting one or more layers in the laminate.

FIG. 3 shows an embodiment of an atomic layer deposition system forprocessing tungsten containing layers and indium containing layersaccording to the teachings of the present invention. The elementsdepicted are those elements necessary for discussion of the presentinvention such that those skilled in the art may practice the presentinvention without undue experimentation.

In FIG. 3, a substrate 310 is located inside a reaction chamber 320 ofALD system 300. Also located within the reaction chamber 320 is aheating element 330 which is thermally coupled to substrate 310 tocontrol the substrate temperature. A gas-distribution fixture 340introduces precursor gases to the substrate 310. Each precursor gasoriginates from individual gas sources 351-354 whose flow is controlledby mass-flow controllers 356-359, respectively. The gas sources 351-354provide a precursor gas either by storing the precursor as a gas or byproviding a location and apparatus for evaporating a solid or liquidmaterial to form the selected precursor gas.

Also included in the ALD system 300 are purging gas sources 361, 362,each of which is coupled to mass-flow controllers 366, 367,respectively. The gas sources 351-354 and the purging gas sources361-362 are coupled by their associated mass-flow controllers to acommon gas line or conduit 370 which is coupled to the gas-distributionfixture 340 inside the reaction chamber 320. Gas conduit 370 is alsocoupled to vacuum pump, or exhaust pump, 381 by mass-flow controller 386to remove excess precursor gases, purging gases, and by-product gases atthe end of a purging sequence from the gas conduit 370.

Vacuum pump, or exhaust pump, 382 is coupled by mass-flow controller 387to remove excess precursor gases, purging gases, and by-product gases atthe end of a purging sequence from the reaction chamber 320. Forconvenience, control displays, mounting apparatus, temperature sensingdevices, substrate maneuvering apparatus, and necessary electricalconnections as are known to those skilled in the art are not shown inFIG. 3. Although ALD system 300 is illustrated as an example, other ALDsystems may be used.

Using ALD methods as described above there are a number of differentprecursor chemistries that can be used to form monolayers includingtungsten, and monolayers including indium. One example chemistry fortungsten nitride includes processing variations of the binary reaction2WF₆+NH₃→W₂N+3HF+9/2F₂. In one example, self-limiting growth occurs atsubstrate temperatures ranging from 600 to 800 K. Another examplechemistry for monolayers including tungsten is sequential exposure ofSi₂H₆ and WF₆. at approximately 10 Torr.

One example of chemistry for indium oxide includes InCl₂ that is reactedwith water. In one example, InCl₂ is oxidized at substrate temperaturesbetween 400 and 500° C. In one embodiment, In₂O₃ films grown with InCl₂and water are polycrystalline with a preferred grain orientation in the[100] direction.

Although examples of precursors, oxidizers, and process conditions arelisted above, the invention is not so limited. One of ordinary skill inthe art, having the benefit of the present disclosure will recognizethat other chemistries and process conditions that form monolayers withtungsten and indium can be used.

FIG. 4 illustrates an electronic device 400 that includes transparentconducting oxide structures formed using monolayer deposition methodssuch as ALD as described above. The electronic device 400 includes afirst component 420 that benefits from transparent conductingstructures. Examples of first component 420 includes LEDs, active pixelsensors, solar cells, a liquid crystal display (LCD) region, acontrolled visibility region of a smart window, gas sensors,electroluminescent (EL) devices etc. In these examples, device operationis improved with transparency to electromagnetic energy such as visiblewavelength light, infrared light, ultra violet light, etc.

In one embodiment, the device 400 further includes a power source 430.The power source 430 is electrically connected to the first component420 using interconnecting circuitry 440. In one embodiment, theinterconnecting circuitry 440 includes tungsten-doped indium oxideformed as a transparent conducting oxide using methods described above.In addition to depositing material as described above, techniques suchas lithography with masks, and/or etching etc. can be used to patternconducting circuitry.

In one embodiment, the device 400 further includes a secondary component410. The secondary component is electrically connected to the firstcomponent 420 using interconnecting circuitry 442. Likewise, in oneembodiment, the interconnecting circuitry 442 includes tungsten-dopedindium oxide formed as a transparent conducting oxide using methodsdescribed above. Examples of secondary components 410 include signalamplifiers, semiconductor memory, logic circuitry or othermicroprocessing circuits, etc. Aside from interconnecting circuitry, inone embodiment, the first component 420 and/or the secondary component410 includes a tungsten-doped indium oxide structure formed as atransparent conducting oxide using methods described above.

FIG. 5 shows one specific example of an electronic device includingtransparent conducting oxides formed as described above. An imagingdevice 500 is shown. The imaging device includes an image sensor 510,with a pixel array 512. In one embodiment the pixel array 512 is coupledto additional row circuitry 514 and column circuitry 516. Examples ofrow and/or column circuitry includes drivers, amplifiers, decoders, etc.In one embodiment, the image sensor 510 is formed on a singlesemiconductor substrate using CMOS processes.

FIG. 5 further shows a logic device 520 coupled to the image sensor 510through circuitry 522. In one embodiment, the logic device 520 includesa programmable logic circuit. Other logic devices includemicroprocessors, etc. In one embodiment, the logic device 520 andcircuitry 522 are formed on the same semiconductor substrate as theimage sensor 510.

A memory device 530 is also shown in FIG. 5. In one embodiment, thememory device is coupled to the logic device 520 using circuitry 524. Inone embodiment, the memory device 530, the logic device 520 andcircuitry 522, 524 are formed on the same semiconductor substrate as theimage sensor 510. An advantage of CMOS processing includes the abilityto form a variety of different devices, such as logic, memory, and imagesensing on a single substrate. Using monolayer deposition processes asdescribed above, tungsten-doped indium oxide conductors can further beformed on a single substrate using CMOS processing equipment.

As shown, example applications of transparent conducting oxides includecircuitry 522, 524 and circuitry within the image sensor 510. Althoughinterconnecting circuitry applications for transparent conducting oxidesare discussed, the invention is not so limited. Other regions andstructures of semiconductor chips where properties such as transparencyand conductivity are important are within the scope of the invention.

While a number of improved features of embodiments of the invention aredescribed, the above lists are not intended to be exhaustive. Althoughspecific embodiments have been illustrated and described herein, it willbe appreciated by those of ordinary skill in the art that anyarrangement that is calculated to achieve the same purpose may besubstituted for the specific embodiment shown. This application isintended to cover any adaptations or variations of the presentinvention. It is to be understood that the above description is intendedto be illustrative and not restrictive. Combinations of the aboveembodiments, and other embodiments, will be apparent to those of skillin the art upon reviewing the above description. The scope of theinvention includes any other applications in which the above structuresand methods are used. The scope of the invention should be determinedwith reference to the appended claims, along with the full scope ofequivalents to which such claims are entitled.

1. A method of forming a transparent conducting oxide component,comprising: forming a plurality of chemically adhered monolayers on asubstrate, including: depositing a first monolayer including tungsten;depositing a second monolayer including indium; processing the pluralityof chemically adhered monolayers to form a tungsten-doped indium oxide,wherein processing includes; annealing the plurality of chemicallyadhered monolayers to form a substantially uniform chemical mixture ofthe monolayers.
 2. The method of claim 1, wherein depositing at least afirst monolayer including tungsten includes depositing a tungsten oxidemonolayer.
 3. The method of claim 1, wherein depositing at least a firstmonolayer including tungsten includes depositing a tungsten nitridemonolayer.
 4. The method of claim 1, wherein depositing at least asecond monolayer including indium includes depositing an indium oxidemonolayer.
 5. The method of claim 1, wherein processing the plurality ofchemically adhered monolayers includes oxidizing metallic monolayers toform a tungsten-doped indium oxide.
 6. The method of claim 1, whereinprocessing the plurality of chemically adhered monolayers includesprocessing substantially amorphous monolayers at a temperature thatforms a substantially amorphous tungsten-doped indium oxide.
 7. Themethod of claim 1, wherein processing the plurality of chemicallyadhered monolayers includes processing the monolayers at a temperaturethat forms a substantially nanocrystalline tungsten-doped indium oxide.8. A method of forming an image sensor, comprising: forming an array ofactive pixel sensors on a substrate; forming a number of signalamplifiers coupled to pixel sensors in the array; forming atungsten-doped indium oxide transparent conducting oxide structurecoupled to the active pixel sensors and the signal amplifiers,including: forming a plurality of chemically self-limiting monolayersconnected between the active pixel sensors and the signal amplifiers,including: depositing at least a first monolayer including tungsten;depositing at least a second monolayer including indium; and annealingthe plurality of chemically self-limiting monolayers to form asubstantially uniform chemical mixture of the monolayers.
 9. The methodof claim 8, wherein the image sensor is formed using only complementarymetal oxide semiconductor (CMOS) processing techniques.
 10. The methodof claim 9, further including forming programmable logic circuitry onthe same substrate as the array of active pixel sensors.
 11. The methodof claim 10, further including forming a memory array on the samesubstrate as the array of active pixel sensors.
 12. The method of claim8, wherein depositing at least a first monolayer including tungstenincludes depositing a W₂N monolayer.
 13. The method of claim 8, whereindepositing at least a second monolayer including indium includesdepositing a In₂O₃ monolayer.
 14. A method of forming an electricaldevice, comprising: forming a first electrical component on a substrate;forming a second electrical component electrically separate from thefirst electrical component; forming a tungsten-doped indium oxidetransparent conducting oxide structure electrically connecting the firstelectrical component and the second electrical component, including:forming a plurality of chemically adhered monolayers, at least two ofwhich have different chemistries, including: depositing at least a firstmonolayer including tungsten; depositing at least a second monolayerincluding indium; and annealing the plurality of chemically adheredmonolayers to form a chemical mixture of the monolayers.
 15. The methodof claim 14, wherein depositing at least a first monolayer includingtungsten includes atomic layer deposition (ALD) of a W₂N monolayer. 16.The method of claim 15, wherein atomic layer deposition (ALD) of a W₂Nmonolayer includes exposing a WF₆ layer to NH₃.
 17. The method of claim14, wherein depositing at least a first monolayer including tungstenincludes sequential exposure of Si₂H₆ and WF₆.
 18. The method of claim14, wherein depositing at least a second monolayer including indiumincludes atomic layer deposition (ALD) of an In₂O₃ monolayer.
 19. Themethod of claim 18, wherein atomic layer deposition (ALD) of a In₂O₃monolayer includes oxidizing InCl₂.
 20. An electrical device,comprising: a first device component; a second device component; and atungsten-doped indium oxide transparent conducting oxide structureelectrically connecting the first and second device component, whereinthe transparent conducting oxide structure is formed by a methodincluding: atomic layer depositing at least a first monolayer includingtungsten; atomic layer depositing at least a second monolayer includingindium; and annealing the monolayers to form a chemical mixture of themono layers.
 21. The electrical device of claim 20, wherein the firstdevice component includes a flat panel display component.
 22. Theelectrical device of claim 20, wherein the first device componentincludes a photovoltaic cell component.
 23. The electrical device ofclaim 20, wherein the first device component includes an electricallydimmable window component.